This invention relates to a novel method for placing a dental post into a tooth root canal, and more particularly, to a dental post system that utilizes a slotted tap and a reverse lentulo drill.
In conventional root canal techniques, it is generally the practice to first form a post-hole in a selected tooth, after which a dental prefabricated post is placed therein. Then, the dentist or dental practitioner builds up the core using a core build-up material, after which a crown is applied thereover.
One example of a prefabricated post is the product FLEXI-POST, manufactured by Essential Dental Systems, Inc. of South Hackensack, N.J. and described in U.S. Pat. Nos. 4,490,116 and RE 31,948. This dental post has a threaded outside for generating grooves into the post hole of a tooth as the post is threadingly inserted therein. The product also has relatively spaced legs that define a longitudinally extending slot. The legs move radially to absorb threading torque and other forces. Therefore, the legs prevent the application of such forces and stresses to the walls of the tooth root so as to permit the dental post to be threaded without fracture of the tooth. In other words, threading the post into the root canal causes the slot of the post to at least partially collapse, thereby reducing stress while the post is being threaded. However, the use of a slotted post such as FLEXI-POST does have certain disadvantages. Since FLEXI-POST is not a solid post, there is the risk of increased metal fatigue.
In many systems used in dentistry today, a substantially solid tap is used to trial thread a root canal. The purpose of the tap is to create the grooves along the post hole in the root canal. Once this is done, a solid post is seated in the post hole in which the grooves were formed by the threads of the previously used tap.
Although at first examination, it would appear that use of a solid tap would produce less stress during insertion than if one simply took a solid threaded post and trial seated it into the root canal. However, use of such a solid tap for creating grooves in the post hole does apply a significant amount of force and stress to the walls of the tooth root, and there is still a risk of fracture to the tooth when using a tap. This is because there is substantially no flexibility between the tooth and the thread formed along the post-hole.
Another problem with most dental post systems is the difficulty of applying cement along the post hole prior to insertion of the dental post. In some systems, a lentulo drill is used, which essentially comprises a spiral wire which sprays cement radially along the post hole. In other words, if the end or apex of the post hole is open, the cement can often be sprayed by the lentulo drill wire beyond the confines of the post hole. This is because of the centrifying action of the spiral--no stop is found on a conventional lentulo drill.
Accordingly, it would be desirable to provide a dental post system including a tap and lentulo drill which overcomes these disadvantages.